1. Field of the Invention
The present invention broadly relates to stump grinders. Specifically, the present invention is a Variable Width Stump Grinder with independently extensible axles. Representative prior art pertinent to motorized stump grinders is found in U.S. Patent Class 144, subclass 2 N.
2. Prior Art
One of the most difficult and time consuming tasks associated with land clearing and tree removal is removal of the stumps. Stumps generally must be removed in order to render land useful for building, cultivation or for aesthetic reasons. Conventional approaches to stump removal are time consuming, costly and oftentimes dangerous. The stumps may be cut out by hand using axes and chain saws. Needless to say this approach is time consuming and hard on equipment. Heavy equipment may be used to dig stumps out or pull them up. This requires space and the use of a large piece of equipment such as a bulldozer. Blasting is a costly method of stump removal and often not practical in an urban setting. Additionally once the stump is removed a problem remains, what to do with it. Many landfills will not accept tree stumps. Burning on site might cause ecological problems and be prohibited by local laws or ordinances. Composting is not very practical from a time standpoint.
The art is replete with machines devised to comminute tree stumps in place. Some of these machines grind the stump away until it is below the surface of the surrounding soil. The devices, utilize a rotating cutting wheel, usually driven by an internal combustion engine.
Forslund, U.S. Pat. No. 4,069,846, discloses a device for eradicating tree stumps which employs a series of hydraulic cylinders and booms to pull apart an already split stump.
Various types of stump grinders or cutters have proven most effective for stump eradication. The prior art attempts share some common elements. Most devices include some form of elongated, rigid frame which rests on two or more wheels. A rotating, cutter blade is employed to engage and reduce the stump. The cutter may be actuated by remote hydraulic controls. Alternatively the cutters may be manually controlled and moved about by the operator.
A manual "push" stump remover is disclosed in U.S. Pat. No. 4,783,914, issued to Bowling Nov. 15, 1988. Another push unit is disclosed in Doskocil, U.S. Pat. No. 4,703,786. U.S. Pat. No. 3,123,112 issued Mar. 3, 1964, discloses a one man stump cutter in which a motor is disposed upon an elongated frame between front mounted wheels and a rear mounted stump cutter assembly.
U S. Pat. No. 3,783,914 discloses a "walk behind" self propelled stump cutter which includes a downwardly projecting cutter wheel disposed between the front support wheels and the rear handles. The latter patent is similar to Carlton, U.S. Pat. No. 3,336,958, issued Aug. 22, 1967. This patent discloses a one man machine in which a front mounted cutter wheel assembly is moved downwardly into engagement with a stump when an operator lifts up on the rear mounted handles. The drive wheels of the device provide the pivot point.
Other stump cutters are intended to be employed as an attachment. Bolton, U.S. Pat. No. 4,697,625, discloses a stump cutter which must be mounted to some other type of structure or frame In U.S. Pat. Nos. 4,180,107 and 4,041,996 Grover discloses stump eradicators intended to be attached to the boom of a crane or other heavy equipment.
Cutter tooth construction and deployment are discussed in McKenry, U.S. Pat. No. 4,214,617.
Various stump cutters intended to be towed into position are disclosed in various U.S. patents. A stump cutter employing a towable frame is illustrated in Smith, U.S. Pat. No. 4,744,396. Other examples of towable stump grinders are U.S. Pat. Nos. 4,271,879; 3,568,740; 4,074,447; RE 28,651; and 3,625,267. Some of the latter devices disclose stump cutting machines in which a variety of hydraulic and other complex linkages are provided for controlling the rotation cutter blade assembly.
On modern building sites many trees are left in place for environmental, ecological, and ascetic purposes. Therefore, it is often necessary to maneuver a stump grinder, capable of handling fairly large stumps, around trees, buildings and fences. Once in position it must be deployed around standing trees. Therefore, it is desirous to provide a stump grinder of a relatively large size which can easily be deployed in a "tight" situation. Such a stump grinder needs to have independently retractable and extensible axles.
Prior art stump cutters and grinders employ fixed axles. Various patents speaking to land vehicles disclose extensible axles such as U.S. Pat. No. 3,330,574 issued to Kulyk on Jul. 11, 1967. Wheels can be expanded forward and backward as seen in Smith, U.S. Pat. No. 4,948,155. U.S. Pat. Nos. 3,698,734 and 4,358,133 both show trailers having wheels that can be extended or contracted.
Hence, it is desirous to provide a stump grinder which may be easily towed behind a relatively small vehicle such as a van or pickup truck, but which has the ability to handle fairly large stumps. Therefore, it is desirous to provide a stump grinder which has an extensible base or stance to provide stability for a relatively large motor and grinding wheel during towing and operation. It is also disable that such a stump grinder also be capable of being deployed without the use of the tow vehicle in tight situations such as through the gates or around existing trees and buildings.
As a result, it is desirous to provide a stump grinder with a rigid frame and extensible axles to provide the necessary extended base. These axles should be independently extensible to facilitate use around existing trees and structures, avoiding damage thereto. Further, the stump grinder needs to be self propelled and capable of being maneuvered by a single individual. Finally, it is desirous that extension of the axles and operation of the grinder be controlled from a central location to facilitate one man use and coordinated use of the axles and the grinding wheel.